To find the new object, scientists used gravitational microlensing technology. As a result
Astrophysicists believe that the Milky Way shouldbe about 100 million rogue black holes. Such objects are formed from heavy stars, the mass of which is more than 20 times the mass of the Sun. At the end of evolution after a supernova explosion, the remnants of the core of such stars collapse. Since this process is not perfectly symmetrical, the resulting black hole gains momentum and begins to move through the galaxy.
A wandering black hole cannot be seen inan ordinary telescope, since it does not emit light, but it distorts space. The massive object deflects and intensifies the starlight from everything that momentarily lines up directly behind her.
This effect is applied in technologygravitational microlensing. Scientists use ground-based telescopes that scan the Milky Way to capture sudden changes in the brightness of stars that could be caused by the passage of a large object. Hubble then examines the events found from space in detail.
An illustration of the gravitational distortion of an object's position. Source: NASA, ESA, STScI, Joseph Olmsted
The researchers note that the technologyGravitational microlensing has made it possible to detect many different objects, including stars and exoplanets. The unique "fingerprint" of the event allows you to accurately determine the type of moving object. In the case of a black hole, very strong gravity lengthens the time for the change in brightness: it will last more than 200 days. In addition, unlike black holes, stars affect not only the brightness, but also the color of the background object when passing between it and the Earth.
When the found black hole passed in front of the backgroundstar located in the galactic bulge at a distance of 19 thousand light years, the light of this star, going to the Earth, was amplified for 270 days, while the black hole passed by. At the same time, there was no color change, astrophysicists say. The Hubble observation showed that the image of the star was shifted from its usual position by about a millisecond of arc.
The reliability of the find is confirmed by the fact thatTwo independent teams of astrophysicists announced the discovery of the object at once: one led by the Space Telescope Science Institute in Baltimore, and the second by the University of California at Berkeley. Both groups of scientists published preprints of their papers for The Astrophysical Journal and The Astrophysical Journal Letters, respectively. Scientists estimate the mass of the found object in different ways, but confirm its presence.
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